Some say that Be’s bright yellow title tabs are one of the interface’s most distinctive features. If you’re not a big fan of yellow, download WindowShade. This utility will let you change the colors of your BeOS title tabs and window borders.

WindowShade is a command-line utility which only accepts hexadecimal parameters for specifying colors. To make life easier, download WSFrontEnd, which is a graphical front-end to WindowShade’s functionality.
Place the WindowShade folder wherever you like, then drop WSFrontEnd into the same folder. Double-click WSFrontEnd and set the colors however you like. When you close WSFrontEnd, it will create a shell script called „setcolors“ in the same folder.
Now all you have to do is specify the path to setcolors in your UserBootscript, so the color changes are restored each time you boot BeOS. Here’s mine:

/boot/apps/utils/WindowShade/setcolors & 

For reference, the default tab colors in BeOS are:
yellow: 255,203,0
grey: 219,219,219